bevy/examples/animation/gltf_skinned_mesh.rs
James Liu 31bd4ecbbc Mesh Skinning. Attempt #3 (#4238)
# Objective
Load skeletal weights and indices from GLTF files. Animate meshes.

## Solution
 - Load skeletal weights and indices from GLTF files.
 - Added `SkinnedMesh` component and ` SkinnedMeshInverseBindPose` asset
 - Added `extract_skinned_meshes` to extract joint matrices.
 - Added queue phase systems for enqueuing the buffer writes.

Some notes:

 -  This ports part of # #2359 to the current main.
 -  This generates new `BufferVec`s and bind groups every frame. The expectation here is that the number of `Query::get` calls during extract is probably going to be the stronger bottleneck, with up to 256 calls per skinned mesh. Until that is optimized, caching buffers and bind groups is probably a non-concern.
 - Unfortunately, due to the uniform size requirements, this means a 16KB buffer is allocated for every skinned mesh every frame. There's probably a few ways to get around this, but most of them require either compute shaders or storage buffers, which are both incompatible with WebGL2.

Co-authored-by: james7132 <contact@jamessliu.com>
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: James Liu <contact@jamessliu.com>
2022-03-29 18:31:13 +00:00

70 lines
2.6 KiB
Rust

use std::f32::consts::PI;
use bevy::{pbr::AmbientLight, prelude::*, render::mesh::skinning::SkinnedMesh};
/// Skinned mesh example with mesh and joints data loaded from a glTF file.
/// Example taken from <https://github.com/KhronosGroup/glTF-Tutorials/blob/master/gltfTutorial/gltfTutorial_019_SimpleSkin.md>
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.insert_resource(AmbientLight {
brightness: 1.0,
..Default::default()
})
.add_startup_system(setup)
.add_system(joint_animation)
.run();
}
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
// Create a camera
commands.spawn_bundle(PerspectiveCameraBundle {
transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
// Spawn the first scene in `models/SimpleSkin/SimpleSkin.gltf`
commands.spawn_scene(asset_server.load::<Scene, _>("models/SimpleSkin/SimpleSkin.gltf#Scene0"));
}
/// The scene hierachy currently looks somewhat like this:
///
/// ```ignore
/// <Parent entity>
/// + Mesh node (without `PbrBundle` or `SkinnedMesh` component)
/// + Skinned mesh entity (with `PbrBundle` and `SkinnedMesh` component, created by glTF loader)
/// + First joint
/// + Second joint
/// ```
///
/// In this example, we want to get and animate the second joint.
/// It is similar to the animation defined in `models/SimpleSkin/SimpleSkin.gltf`.
fn joint_animation(
time: Res<Time>,
parent_query: Query<&Parent, With<SkinnedMesh>>,
children_query: Query<&Children>,
mut transform_query: Query<&mut Transform>,
) {
// Iter skinned mesh entity
for skinned_mesh_parent in parent_query.iter() {
// Mesh node is the parent of the skinned mesh entity.
let mesh_node_entity = skinned_mesh_parent.0;
// Get `Children` in the mesh node.
let mesh_node_children = children_query.get(mesh_node_entity).unwrap();
// First joint is the second child of the mesh node.
let first_joint_entity = mesh_node_children[1];
// Get `Children` in the first joint.
let first_joint_children = children_query.get(first_joint_entity).unwrap();
// Second joint is the first child of the first joint.
let second_joint_entity = first_joint_children[0];
// Get `Transform` in the second joint.
let mut second_joint_transform = transform_query.get_mut(second_joint_entity).unwrap();
second_joint_transform.rotation = Quat::from_axis_angle(
Vec3::Z,
0.5 * PI * time.time_since_startup().as_secs_f32().sin(),
);
}
}